(1) Field of the Invention
The present invention relates to a method of transmitting print data to a printing apparatus, especially to a push printing when document data consists of a plurality of print objects formatted differently.
(2) Description of the Related Art
Recently, connecting a printing apparatus to an AV (Audio Visual) device such as a digital camera and a digital broadcast receiver (STB: Set Top Box) or the like in order to directly print a video that is shot or received by an AV device has been attempted.
Whichever AV device it may be that sends print instructions, it is desirable to obtain the same printing result at any time and also to reduce a processing of load on the side of a host device. Therefore, a print protocol which allows the print document data shot or received by the AV device to be directly transmitted from the AV device to the printing apparatus and also allows the printer side to perform processing to generate print picture data is necessary.
As one of the resolutions to respond to such a request, a Printer Subunit, one of the AV/C protocols defined by an IEEE 1394 standard, can be cited. The AV/C protocol relates to a connection of the AV devices, determines a standard protocol of basic essentials, maintains the compatibility, and provides a framework in which each maker can respectively enhance the functions of the device. Among the AV/C protocols mentioned above, the one which defines the AV/C command regarding especially the printing apparatus is called AV/C Printer Subunit. The detail concerning the AV/C Printer Subunit is described in “TA Document 1999038 AV/C Printer Subunit Specification 1.0” which is available at http://www.1394TA.org. The Printer Subunit defines a push printing of still picture data when a still picture is transmitted from the AV device to the printing apparatus for printing.
FIG. 1 is a sequence diagram showing an example of a communication procedure when an AV device such as a digital camera outputs a picture to a printing apparatus according to the existing AV/C Printer Subunit. Here, a communication sequence for outputting a print object such as a picture stored in a controller 900 connected via the IEEE 1394 bus to a printer unit (a printing apparatus) 910 as well as commands and responses then communicated are shown.
Firstly, the controller 900 obtains version information from the printer unit 910 (version verification phase) and establishes a logical transmission channel (a connection for Asynchronous data transmission; Asynchronous Connection) after specifying a job identifier job_ID for the printer unit 910 and then generating a print job (job creation phase).
The controller 900 then specifies a print object that it desires to output by sending an AV/C command CAPTURE to the printer unit 910 and outputs (push) the specified print object to the printer unit 910 via the transmission channel after instructing the printer unit 910 to receive the print object (object push phase).
When the printing is complete and an ACCEPTED response indicating end status is sent back from the printer unit 910 to the controller 900, the controller 900 disconnects the transmission channel of Asynchronous Connection (disconnection phase) and performs polling for the status of the job at the printer unit 910 (status poll phase) after closing the print job (job closure phase).
In this way, the printout is realized by the fact that the AV device outputs the print object to the printing apparatus according to the AV/C Printer Subunit without installing driver software unique to the printing apparatus.
Meanwhile, as for a print format such as HTML widely used for a document data delivery on the Internet today and XHTML-Print which has attracted attention recently, a single print document consists of a plurality of data (print object) described in different formats. In order to generate a print picture from a print document described with such XHTML-Print or the like, it is required to access randomly to a plurality of print objects described in different formats.
However, the printing apparatus cannot judge to which extent of push transmission the print document is composed of since the end of the transmission is not clearly shown when the access system mentioned above is realized by applying the aforementioned N column printing so as to store the print objects in the printing apparatus by sequentially push transmitting the print objects. Also, the printing apparatus cannot judge which type of print document a plurality of the print objects to be sequentially transmitted form. The same goes with other push printing protocols starting with the AV/C Printer Subunit and such a push printing protocol that push transmits all at once a plurality of data described in different formats from an AV device (a print data providing device) to a printing apparatus does not exist.
Therefore, in order to realize a system in which the same printing result can be obtained at any time when printing data described in a format such as XHTML-Print or the like using whichever type of AV device, it is required to apply a pull print protocol with which a printing apparatus performs generating processing of print picture data while sequentially requesting necessary print objects from an AV device.
The Japanese Application number 2002-024578 refers to a pull print protocol (an extension method of the AV/C Printer Submit is taken as an example) which enables a pull print of any form of print document including a print document consisting of a plurality of print objects described in different formats such as XHTML-Print.
However, a prior pull print protocol starting with the AV/C Printer Subunit contains a problem of increase in communication traffic since it is a printing apparatus that requests (pull) sequentially the print objects stored in the host side.